Peering into a dugout and seeing the bottom is only a dream for many prairie farmers.
But the Prairie Farm Rehabilitation Administration says farm dugout water can be made as clear as what comes out of city taps. The answer is coagulation, usually the first step in urban water treatment systems.
A metal salt is dissolved in the water. Floating particles stick to the salt and sink to the bottom, forming a stable sediment.
The process removes silt, phosphates, organic carbon and minerals such as aluminum, iron and manganese from the water and prepares it for further treatment such as chlorination or ultraviolet light exposure.
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Larry Braul of the PFRA in Regina said water’s appearance and odour can be improved by 80 percent.
Braul, who has worked extensively on the process, said it does such a good job of cleaning water that the results can be deceiving.
“It looks good enough to drink, but that isn’t the case. It needs to tested and usually more treatment is required.”
Coagulation does not remove bacteria. Instead, it produces safer and more palatable water that can either be treated for drinking water or used to achieve better results for agricultural spraying and livestock watering.
Reducing phosphate in the water will also drastically reduce the incidence of algae blooms.
The PFRA has been working with farmers for several years and says the process is simple, inexpensive and yields dramatic results.
Aluminum sulfate, or alum, is the most common chemical used for treating a dugout, costing between $200 and $1,000 per application, depending on the size of reservoir. The chemical is widely available from prairie chemical dealers.
The process requires a small boat with an outboard motor, up to 410 litres of metal salts, a chemical apron, eye protection and gloves, a pH and alkaline test kit, a small pump capable of moving eight litres per minute and a hose to get the chemicals to the boat propeller.
Producers first need to estimate the volume of their dugout so that they can calculate the amount of coagulant to add, providing a proper pH balance and alkalinity.
The test is straight forward, and needs a two-litre measure, a couple of 10 to 25 millilitre syringes, a plastic spatula, a pH meter and-or alkalinity test strips, and one percent mix of the alum solution.
Mix five ml of the liquid alum with 500 ml of distilled water to get the one percent mix and draw a measured amount into a couple of syringes.
Use the syringes to add, drop by drop, the alum solution to one litre of dugout water, and mix. Test the water until it reaches a pH of about six and-or the alkalinity concentration is 40 milligrams per litre.
This will show how many millilitres of solution per litre of dugout water is needed to treat the reservoir.
The amount of required alum can then be calculated. Remember that the solution added to the one L sample of dugout water was diluted to one percent.
A dugout volume calculator is posted on Alberta Agriculture’s website at www.agric.gov.ab.ca/calculator/dugout.
html. Most dugouts have been built to standard sizes and have a 4:1 end slope and 1.5:1 side slope. The calculation is relatively simple if the depth, width and length are known.
Moor the boat one third of the distance to one end and one third of the distance across with the boat pointed at the nearest end.
Run the engine at full throttle for 20 minutes, thoroughly stirring the reservoir. Pump the coagulant to the propeller at between eight and 20 L per minute. It should take no more than 30 minutes to empty a 205 L barrel. Add half to three quarters of the chemical, continue to mix for 20 minutes and then test the pH and-or alkalinity at several points in the dugout.
If the tests are above a pH of six or an alkalinity of 40 mg/L, then continue adding chemical until the water test reaches the desired level. Too much chemical can damage the water supply so care is needed at this stage. Once the last of the chemical has been added, mix for an additional 20 minutes. After one or two days, the dugout will have settled and the results should be clear.
Researchers said treating in the spring has a slight advantage over fall.
The PFRA said it can provide assistance to producers planning to treat their dugouts and several fact sheets are available at www.agr.ca/pfra/
water/wqualite.htm#treat.
